Ternary compositions for low-capacity refrigeration

ABSTRACT

Compositions containing 2,3,3,3-tetrafluoropropene and to the uses thereof as heat transfer fluid, expansion agents, solvents and aerosol. Compositions essentially containing between 10 and 90 wt. % of 2,3,3,3-tetrafluoropropene, between 5 and 80 wt. % of HFC-134 a  and between 5 and 10 wt. % of HFC-32. Compositions essentially containing from 10 to 45% by weight of 2,3,3,3-tetrafluoropropene, from 50 to 80% by weight of HFC-134 a  and from 5 to 10% by weight of HFC-32.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.13/393,640, filed on Mar. 1, 2012, which is a U.S. national stage ofInternational Application No. PCT/FR2010/051747, filed on Aug. 20, 2010,which claims the benefit of French Application No. 0956249, filed onSep. 11, 2009. The entire contents of each of U.S. application Ser. No.13/393,640, International Application No. PCT/FR2010/051747, and FrenchApplication No. 0956249 are hereby incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present invention relates to compositions containing2,3,3,3-tetrafluoropropene and uses thereof as heat-transfer fluids,blowing agents, solvents and aerosols.

BACKGROUND

The problems posed by substances which delete the atmospheric ozonelayer (ODP: ozone depletion potential) were addressed in Montreal, wherethe protocol imposing a reduction in the production and use ofchlorofluorocarbons (CFCs) was signed. This protocol has been thesubject of amendments which have required that CFCs be withdrawn andhave extended regulatory control to other products, includinghydrochlorofluorocarbons (HCFCs).

The refrigeration and air-conditioning industry has invested a greatdeal in the replacement of these refrigerants, and as a result,hydrofluorocarbons (HFCs) have been marketed.

The (hydro)chlorofluorocarbons used as blowing agents or solvents havealso been replaced with HFCs.

In the automotive industry, the air-conditioning systems for vehiclessold in many countries have changed from a chlorofluorocarbon (CFC-12)refrigerant to a hydrofluorocarbon (1,1,1,2-tetrafluoroethane: HFC-134a)refrigerant which is less harmful to the ozone layer. However, from theviewpoint of the objectives set by the Kyoto protocol, HFC-134a(GWP=1300) is considered to have a high warming potential. Thecontribution to the greenhouse effect of a fluid is quantified by acriterion, the GWP (global warming potential) which indexes the warmingpotential by taking a reference value of 1 for carbon dioxide.

Since carbon dioxide is non-toxic and non-flammable and has a very lowGWP, it has been proposed as a refrigerant in air-conditioning systemsas a replacement for HFC-134a. However, the use of carbon dioxide hasseveral drawbacks, in particular linked to the very high pressure atwhich it is used as a refrigerant in the existing apparatuses andtechnologies.

Document WO 2004/037913 discloses the use of compositions comprising atleast one fluoroalkene having three or four carbon atoms, in particularpentafluoropropene and tetrafluoropropene, preferably having a GWP atmost of 150, as heat-transfer fluids.

Document WO 2005/105947 teaches the addition to tetrafluoropropene,preferably 1,3,3,3-tetrafluoropropene, of a blowing coagent such asdifluoromethane, penta-fluoroethane, tetrafluoroethane, difluoroethane,heptafluoropropane, hexafluoropropane, pentafluoropropane,pentafluorobutane, water and carbon dioxide.

Document WO 2006/094303 discloses binary compositions of2,3,3,3-tetrafluoropropene (HFO-1234yf) with difluoromethane (HFC-32),and of 2,3,3,3-tetrafluoropropene with 1,1,1,2-tetrafluoroethane(HFC-134a).

Quaternary mixtures comprising 1,1,1,2,3-pentafluoropropene (HFO-1225ye)in combination with difluoromethane, 2,3,3,3-tetrafluoropropene andHFC-134a were disclosed in this document. However,1,1,1,2,3-pentafluoropropene is toxic.

Quaternary mixtures comprising 2,3,3,3-tetrafluoropropene in combinationwith iodotrifluoromethane (CF₃I), HFC-32 and HFC-134a have also beendisclosed in document WO 2006/094303. However, CF₃I has a non-zero ODPand poses stability and corrosion problems.

The applicant has now developed 2,3,3,3-tetrafluoropropene compositionswhich do not have the abovementioned drawbacks and have both a zero ODPand a GWP which is lower than that of the existing heat-transfer fluidssuch as and HFC-134a.

DETAILED DESCRIPTION

The compositions used as heat-transfer fluid in the present inventionhave values for the temperatures at the compressor outlet, and pressurelevels, equivalent to the values given by HFC-134a. The compressionratios are lower. These compositions can replace HFC-134a withoutchanging compressor technology.

The compositions used as a heat-transfer fluid in the present inventionhave volume capacities which are greater than the volume capacity ofHFC-134a (between 116 and 133%). By virtue of these properties, thesecompositions can use smaller compressors and have the same heating orcooling capacity.

The compositions according to the present invention are characterized inthat they essentially contain from 10 to 90% by weight of2,3,3,3-tetrafluoropropene, from 5 to 80% by weight of HFC-134a and from5 to 10% by weight of HFC-32.

Preferably, the compositions essentially contain from 10 to 45% byweight of 2,3,3,3-tetrafluoropropene, from 50 to 80% by weight ofHFC-134a and from 5 to 10% by weight of HFC-32.

The compositions according to the present invention can be used asheat-transfer fluids, preferably in compression systems andadvantageously with exchangers operating in counterflow mode or incross-flow mode with counterflow tendency. They are particularlysuitable for systems of low-capacity refrigeration per unit volume sweptby the compressor.

In compression systems, the heat exchange between the refrigerant andthe heat sources takes place by means of heat-transfer fluids. Theseheat-transfer fluids are in the gaseous state (the air inair-conditioning and direct expansion refrigeration), liquid state (thewater in domestic heat pumps, glycolated water) or two-phase state.

There are various modes of transfer:

-   -   the two fluids are arranged in parallel and travel in the same        direction: co-flow (antimethodic) mode;    -   the two fluids are arranged in parallel but travel in the        opposite direction: counterflow (methodic) mode;    -   the two fluids are positioned perpendicularly: cross-flow mode.        The cross-flow may be with co-flow or counterflow tendency;    -   one of the two fluids makes a U-turn in a wider pipe, which the        second fluid passes through. This configuration is comparable to        a co-flow exchanger over half the length, and for the other        half, to a counterflow exchanger: pinhead mode.

The compositions according to the present invention are advantageouslyused in stationary air conditioning and heat pumps, preferably as areplacement for HFC-134a.

The compositions according to the present invention can be stabilized.The stabilizer preferably represents at most 5% by weight relative tothe total composition.

As stabilizers, mention may in particular be made of nitromethane,ascorbic acid, terephthalic acid, azoles such as tolutriazole orbenzotriazole, phenolic compounds such as tocopherol, hydroquinone,t-butyl hydroquinone or 2,6-di-tert-butyl-4-methylphenol, epoxides(alkyl, optionally fluorinated or perfluorinated, or alkenyl oraromatic) such as n-butyl glycidyl ether, hexanediol diglycidyl ether,allyl glycidyl ether or butylphenyl glycidyl ether, phosphites,phosphates, phosphonates, thiols and lactones.

The compositions according to the present invention, as a heat-transferagent, can be employed in the presence of lubricants such as mineraloil, alkylbenzene, polyalkylene glycol and polyvinyl ether.

The compositions according to the present invention can also be used asblowing agents, aerosols and solvents.

EXPERIMENTAL SECTION Calculation Tools

The RK-Soave equation is used for calculating the densities, enthalpies,entropies and liquid/vapor equilibrium data of the mixtures. The use ofthis equation requires knowledge of the properties of the pure bodiesused in the mixtures in question and also the interaction coefficientsfor each binary mixture.

The Data Required for Each Pure Body are:

The boiling point, the critical temperature and the critical pressure,the curve of pressure as a function of temperature starting from theboiling point up to the critical point, and the saturated liquid andsaturated vapor densities as a function of temperature.

HFC-32, HFC-134a:

The data on these products aer published in the ASHRAE Handbook 2005chapter 20, and are also available from Refrop (software developed byNIST for calculating the properties of refrigerants).

HFO-1234yf

The data of the temperature-pressure curve for HFO-1234yf are measuredby the static method. The critical temperature and the critical pressureare measured using a C80 calorimeter sold by Setaram. The densities, atsaturation as a function of temperature, are measured using thevibrating tube densitometer technology developed by the laboratories ofthe Ecole des Mines of Paris.

Interaction Coefficient of the Binary Mixtures:

The RK-Soave equation uses binary interaction coefficients to representthe behavior of the products in mixtures. The coefficients arecalculated as a function of the experimental liquid/vapor equilibriumdata.

The technique used for the liquid/vapor equilibrium measurements is thestatic-cell analytical method. The equilibrium cell comprises a sapphiretube and is equipped with two electromagnetic ROLSITM samplers. It isimmersed in a cryothermostat bath (HUBER HS40). A magnetic stirrer witha field drive rotating at varying speed is used to accelerate reachingthe equilibria. The analysis of the samples is carried out by gaschromatography (HP5890 series II) using a katharometer (TCD).

HFC-32/HFO-1234yf, HFC-134a/H FO-1234yf:

The liquid/vapor equilibrium measurements on the binary mixtureHFC-32/HFO-1234yf are carried out for the following isotherms: −10° C.,30° C. and 70° C.

The liquid/vapor equilibrium measurements on the binary mixtureHFC-134a/HFO-1234yf are carried out for the following isotherms: 20° C.

HFC-32/HFO-134a:

The liquid/vapor equilibrium data for the binary mixture HFC-134a/HFC-32are available from Refprop. Two isotherms (−20° C. and 20° C.) and oneisobar (30 bar) are used to calculate the interaction coefficients forthis binary mixture.

Compression System: A compression system equipped with a counterflowcondenser and evaporator, with a screw compressor and with an expansionvalve is considered.

The system operates with 15° C. of overheat and 5° C. of undercooling.The minimum temperature difference between the secondary fluid and therefrigerant is considered to be about 5° C.

The isentropic efficiency of the compressors depends on the compressionratio. This efficiency is calculated according to the followingequation:

$\begin{matrix}{\eta_{isen} = {a - {b\left( {\tau - c} \right)}^{2} - \frac{d}{\tau - e}}} & (1)\end{matrix}$

For a screw compressor, the constants a, b, c, d and e of the isentropicefficiency equation (1) are calculated according to the standard datapublished in the “Handbook of air conditioning and refrigeration, page11.52”.

The % CAP is the percentage of the ratio of the volumetric capacitysupplied by each product over the capacity of HFC-134a.

The coefficient of performance (COP) is defined as being the usefulpower supplied by the system over the power provided or consumed by thesystem.

The Lorenz coefficient of performance (COPLorenz) is a referencecoefficient of performance. It is a function of temperatures and is usedfor comparing the COPs of various fluids.

The Lorenz coefficient of performance is defined as follows:

(The temperatures T are in K)

T _(average) ^(condenser) =T _(inlet) ^(condenser) −T _(outlet)^(condenser)   (2)

T _(average) ^(evaporator) =T _(outlet) ^(evaporator) −T _(inlet)^(evaporator)   (3)

The Lorenz COP in the case of air-conditioning and refrigeration is:

$\begin{matrix}{{COPlorenz} = \frac{T_{average}^{evaporator}}{T_{average}^{condenser} - T_{average}^{evaporator}}} & (4)\end{matrix}$

The Lorenz COP in the case of heating is:

$\begin{matrix}{{COPlorenz} = \frac{T_{average}^{condenser}}{T_{average}^{condenser} - T_{average}^{evaporator}}} & (5)\end{matrix}$

For each composition, the coefficient of performance of the Lorenz cycleis calculated as a function of the corresponding temperatures.

The % COP/COPLorenz is the ratio of the COP of the system relative tothe COP of the corresponding Lorenz cycle.

Heating Mode Results:

In heating mode, the compression system operates between a temperaturefor inlet of the refrigerant into the evaporator of −5° C. and atemperature for inlet of the refrigerant into the condenser of 50° C.The system supplies heat at 45° C.

The performance levels of the compositions according to the inventionunder the heating mode operating conditions are given in table 1. Thevalues of the constituents (HFO-1234yf, HFC-32, HFC-134a) for eachcomposition are given as percentage by weight.

TABLE 1 Evap outlet Comp outlet Cond outlet Evap P Cond P Ratio Comp % %COP/ temp (° C.) temp (° C.) T (° C.) (bar) (bar) (w/w) Glide efficiencyCAP COPLorenz HFC-134a −5 81 50 2.4 13.2 5.4 0.00 75.9 100 63.3HFO-1234yf HFC-32 HFC-134a 50 10 40 −2 78 46 3.4 15.6 4.5 2.66 79.4 13064.7 25 10 65 −2 82 47 3.3 15.4 4.7 2.55 78.7 128 65.0 10 10 80 −3 84 473.1 15.1 4.8 2.44 78.3 126 65.1

Cooling or Air-Conditioning Mode Results

In cooling mode, the compression system operates between a temperaturefor inlet of the refrigerant into the evaporator of −5° C. and atemperature for inlet of the refrigerant into the condenser of 50° C.The system supplies refrigeration at 0° C.

The performance levels of the compositions according to the inventionunder the cooling mode operating conditions are given in table 2. Thevalues of the constituents (HFO-1234yf, HFC-32, HFC-134a) for eachcomposition are given as percentage by weight.

TABLE 2 Evap outlet Comp outlet Cond outlet Evap P Cond P Ration Comp %% COP/ temp (° C.) temp (° C.) T (° C.) (bar) (bar) (w/w) Glideefficiency CAP COPLorenz HFC-134a −5 81 50 2.4 13.2 5.4 0.00 75.9 10054.1 HFO-1234yf HFC-32 HFC-134a 65 10 25 −2 76 45 3.5 15.5 4.4 2.87 79.7133 55.8 50 10 40 −2 78 46 3.4 15.6 4.5 2.66 79.4 133 56.0 25 10 65 −282 47 3.3 15.4 4.7 2.55 78.7 132 56.5 15 5 80 −4 81 48 2.9 14.3 5.0 1.3877.6 116 55.6 10 10 80 −3 84 47 3.1 15.1 4.8 2.44 78.3 130 56.7

1. A composition consisting essentially of from 10 to 90% by weight of2,3,3,3-tetrafluoropropene, from 5 to 80% by weight of HFC-134a and from5 to 10% by weight of HFC-32.
 2. The composition as claimed in claim 1,characterized in that it consists essentially of from 10 to 45% byweight of 2,3,3,3-tetrafluoropropene, from 50 to 80% by weight ofHFC-134a and from 5 to 10% by weight of HFC-32.
 3. The composition asclaimed in claim 1, characterized in that it further contains astabilizer.
 4. A heat-transfer fluid comprising the composition asclaimed in claim
 1. 5. A compression refrigeration systems withexchangers operating in counterflow mode containing a heat-transferfluid as claimed in claim
 4. 6. The heat-transfer fluid as claimed inclaim 4, wherein it is used as a replacement for HFC-134a.
 7. Thecompression refrigeration system as claimed in claim 4 characterized inthat it further contains a lubricant.
 8. Blowing agents comprising thecomposition as claimed in claim
 1. 9. Solvents comprising thecomposition as claimed in claim
 1. 10. Aerosols comprising thecomposition as claimed in claim 1.